/*
* Artificial Intelligence for Humans
* Volume 1: Fundamental Algorithms
* Scala Version
* http://www.aifh.org
* http://www.jeffheaton.com
*
* Code repository:
* https://github.com/jeffheaton/aifh

* Copyright 2013 by Jeff Heaton
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package com.heatonresearch.aifh.error

/**
 * The sum of squares method (ESS) measures the error as the sum of the squared difference of each vector element.
 * <p/>
 * http://www.heatonresearch.com/wiki/Sum_of_Squares_Error
 */
class ErrorCalculationESS extends AbstractErrorCalculation {
  /**
   * Calculate the error with ESS.
   *
   * @return The current error.
   */
  override def calculate: Double = {
    if (setSize == 0)
      Double.PositiveInfinity
    else
      globalError / 2
  }
}